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Donenfeld" , Tejun Heo , Lai Jiangshan , "Matthias Brugger" , AngeloGioacchino Del Regno CC: , , , , "Guoyong Wang" Subject: [PATCH] random: Fix the issue of '_might_sleep' function running in an atomic contex Date: Mon, 18 Mar 2024 15:53:27 +0800 Message-ID: <20240318075327.26318-1-guoyong.wang@mediatek.com> X-Mailer: git-send-email 2.18.0 MIME-Version: 1.0 X-TM-AS-Product-Ver: SMEX-14.0.0.3152-9.1.1006-23728.005 X-TM-AS-Result: No-10--3.305300-8.000000 X-TMASE-MatchedRID: GSiycdxM5vtW/DiEtl1O86wxbZnudyr7reJWlnSW7AzFJnEpmt9OEwef 5FoKtUGzyEeGCxgB/y0u5ed2FW2K2WA2IAXETeuKI0cHLI6lhgLt/okBLaEo+C3FY27PpHmsrW4 1+BBqq+/5NLTowdvTKMhRl2j/G5EDdejbiw/Um0KEryjhqiyzyitovaaHxlUrXFNHTRKzg/pm+j 6YVbX2YOmpHB3eYmnZsvQLAMZPkyUGSS/0WwytR4+YSzwl92XTu4ICdvW94WGAZpvTq6Jh4cS4G +2ecnOxNgHYUSdPXp2+LT/N9L0eANL8YenPOW5EPey2g5E3u1vJAXSoafphsVdwRHrgRcbqWmrY r8SaWTXFvFNUfOxLYhIlVYCqhV5OHxPMjOKY7A9t1O49r1VEa8RB0bsfrpPI0PU0TdJoUte6AOO V0y1r/Y9WMC5C2SBsqQcdrSfVFJ8mPBzXYStCYO4nGk5zzAi/lq6sb0EeGWq1Khzt1zZu8G2Ynp iHC6gVvqJlNl3XQXCOh+wyNBrFXDJiNuKohDcKzKSG3JdyKAPqtV2AGMNPavWdclq8lU1q X-TM-AS-User-Approved-Sender: No X-TM-AS-User-Blocked-Sender: No X-TMASE-Result: 10--3.305300-8.000000 X-TMASE-Version: SMEX-14.0.0.3152-9.1.1006-23728.005 X-TM-SNTS-SMTP: 2290C989DD72737292ADF789F77AAC644350473F9635B32C6ACEF6B4E6F677C52000:8 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240318_005455_624512_3CB3B47E X-CRM114-Status: GOOD ( 15.39 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 'input_handle_event' runs in an atomic context (spinlock). In rare instances, it may call the '_might_sleep' function, which could trigger a kernel exception. Backtrace: [] die+0xa8/0x2fc [] bug_handler+0x44/0xec [] brk_handler+0x90/0x144 [] do_debug_exception+0xa0/0x148 [] el1_dbg+0x60/0x7c [] el1h_64_sync_handler+0x38/0x90 [] el1h_64_sync+0x64/0x6c [] __might_resched+0x1fc/0x2e8 [] __might_sleep+0x44/0x7c [] cpus_read_lock+0x1c/0xec [] static_key_enable+0x14/0x38 [] crng_set_ready+0x14/0x28 [] execute_in_process_context+0xb8/0xf8 [] _credit_init_bits+0x118/0x1dc [] add_timer_randomness+0x264/0x270 [] add_input_randomness+0x38/0x48 [] input_handle_event+0x2b8/0x490 [] input_event+0x6c/0x98 Signed-off-by: Guoyong Wang --- drivers/char/random.c | 2 +- include/linux/workqueue.h | 1 + kernel/workqueue.c | 26 ++++++++++++++++++++++++++ 3 files changed, 28 insertions(+), 1 deletion(-) diff --git a/drivers/char/random.c b/drivers/char/random.c index 456be28ba67c..00be9426a6fc 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -719,7 +719,7 @@ static void __cold _credit_init_bits(size_t bits) if (orig < POOL_READY_BITS && new >= POOL_READY_BITS) { crng_reseed(NULL); /* Sets crng_init to CRNG_READY under base_crng.lock. */ if (static_key_initialized) - execute_in_process_context(crng_set_ready, &set_ready); + execute_in_non_atomic_context(crng_set_ready, &set_ready); atomic_notifier_call_chain(&random_ready_notifier, 0, NULL); wake_up_interruptible(&crng_init_wait); kill_fasync(&fasync, SIGIO, POLL_IN); diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index 158784dd189a..eb17c62d23aa 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -550,6 +550,7 @@ extern void drain_workqueue(struct workqueue_struct *wq); extern int schedule_on_each_cpu(work_func_t func); int execute_in_process_context(work_func_t fn, struct execute_work *); +int execute_in_non_atomic_context(work_func_t fn, struct execute_work *ew); extern bool flush_work(struct work_struct *work); extern bool cancel_work(struct work_struct *work); diff --git a/kernel/workqueue.c b/kernel/workqueue.c index bf2bdac46843..8f212346da7a 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -4449,6 +4449,32 @@ int execute_in_process_context(work_func_t fn, struct execute_work *ew) } EXPORT_SYMBOL_GPL(execute_in_process_context); +/** + * execute_in_non_atomic_context - reliably execute the routine with user context + * @fn: the function to execute + * @ew: guaranteed storage for the execute work structure (must + * be available when the work executes) + * + * Schedules the function for delayed execution if atomic context is available, + * otherwise executes the function immediately . + * + * Return: 0 - function was executed + * 1 - function was scheduled for execution + */ +int execute_in_non_atomic_context(work_func_t fn, struct execute_work *ew) +{ + if (!in_atomic()) { + fn(&ew->work); + return 0; + } + + INIT_WORK(&ew->work, fn); + schedule_work(&ew->work); + + return 1; +} +EXPORT_SYMBOL_GPL(execute_in_non_atomic_context); + /** * free_workqueue_attrs - free a workqueue_attrs * @attrs: workqueue_attrs to free